Merge pull request #868 from narfbg/develop-db-oci8

Improve the Oracle (oci8) database driver

4 files changed, 569 insertions, 145 deletions

diff --git a/system/database/drivers/oci8/oci8_driver.php b/system/database/drivers/oci8/oci8_driver.php
index 45b0198eb..0a96f3f6d 100644
--- a/system/database/drivers/oci8/oci8_driver.php
+++ b/system/database/drivers/oci8/oci8_driver.php
@@ -46,7 +46,6 @@
  * permit access to oracle databases
  *
  * @author	  Kelly McArdle
- *
  */
 class CI_DB_oci8_driver extends CI_DB {
 
@@ -68,7 +67,7 @@ class CI_DB_oci8_driver extends CI_DB {
 	protected $_random_keyword = ' ASC'; // not currently supported
 
 	// Set "auto commit" by default
-	protected $_commit = OCI_COMMIT_ON_SUCCESS;
+	public $commit_mode = OCI_COMMIT_ON_SUCCESS;
 
 	// need to track statement id and cursor id
 	public $stmt_id;
@@ -207,12 +206,13 @@ class CI_DB_oci8_driver extends CI_DB {
 	 */
 	protected function _execute($sql)
 	{
-		// oracle must parse the query before it is run. All of the actions with
-		// the query are based on the statement id returned by ociparse
+		/* Oracle must parse the query before it is run. All of the actions with
+		 * the query are based on the statement id returned by oci_parse().
+		 */
 		$this->stmt_id = FALSE;
 		$this->_set_stmt_id($sql);
 		oci_set_prefetch($this->stmt_id, 1000);
-		return @oci_execute($this->stmt_id, $this->_commit);
+		return @oci_execute($this->stmt_id, $this->commit_mode);
 	}
 
 	/**
@@ -238,8 +238,7 @@ class CI_DB_oci8_driver extends CI_DB {
 	 */
 	public function get_cursor()
 	{
-		$this->curs_id = oci_new_cursor($this->conn_id);
-		return $this->curs_id;
+		return $this->curs_id = oci_new_cursor($this->conn_id);
 	}
 
 	// --------------------------------------------------------------------
@@ -247,19 +246,19 @@ class CI_DB_oci8_driver extends CI_DB {
 	/**
 	 * Stored Procedure.  Executes a stored procedure
 	 *
-	 * @param	string	package stored procedure is in
-	 * @param	string	stored procedure to execute
+	 * @param	string	package name in which the stored procedure is in
+	 * @param	string	stored procedure name to execute
 	 * @param	array	parameters
-	 * @return	object
+	 * @return	mixed
 	 *
 	 * params array keys
 	 *
 	 * KEY	  OPTIONAL	NOTES
-	 * name		no		the name of the parameter should be in :<param_name> format
-	 * value	no		the value of the parameter.  If this is an OUT or IN OUT parameter,
-	 *					this should be a reference to a variable
-	 * type		yes		the type of the parameter
-	 * length	yes		the max size of the parameter
+	 * name		no	the name of the parameter should be in :<param_name> format
+	 * value	no	the value of the parameter.  If this is an OUT or IN OUT parameter,
+	 *				this should be a reference to a variable
+	 * type		yes	the type of the parameter
+	 * length	yes	the max size of the parameter
 	 */
 	public function stored_procedure($package, $procedure, $params)
 	{
@@ -274,24 +273,24 @@ class CI_DB_oci8_driver extends CI_DB {
 		}
 
 		// build the query string
-		$sql = "begin $package.$procedure(";
+		$sql = 'BEGIN '.$package.'.'.$procedure.'(';
 
 		$have_cursor = FALSE;
 		foreach ($params as $param)
 		{
-			$sql .= $param['name'] . ",";
+			$sql .= $param['name'].',';
 
-			if (array_key_exists('type', $param) && ($param['type'] === OCI_B_CURSOR))
+			if (isset($param['type']) && $param['type'] === OCI_B_CURSOR)
 			{
 				$have_cursor = TRUE;
 			}
 		}
-		$sql = trim($sql, ",") . "); end;";
+		$sql = trim($sql, ',') . '); END;';
 
 		$this->stmt_id = FALSE;
 		$this->_set_stmt_id($sql);
 		$this->_bind_params($params);
-		$this->query($sql, FALSE, $have_cursor);
+		return $this->query($sql, FALSE, $have_cursor);
 	}
 
 	// --------------------------------------------------------------------
@@ -347,7 +346,7 @@ class CI_DB_oci8_driver extends CI_DB {
 		// even if the queries produce a successful result.
 		$this->_trans_failure = ($test_mode === TRUE) ? TRUE : FALSE;
 
-		$this->_commit = OCI_DEFAULT;
+		$this->commit_mode = (is_php('5.3.2')) ? OCI_NO_AUTO_COMMIT : OCI_DEFAULT;
 		return TRUE;
 	}
 
@@ -371,9 +370,8 @@ class CI_DB_oci8_driver extends CI_DB {
 			return TRUE;
 		}
 
-		$ret = oci_commit($this->conn_id);
-		$this->_commit = OCI_COMMIT_ON_SUCCESS;
-		return $ret;
+		$this->commit_mode = OCI_COMMIT_ON_SUCCESS;
+		return oci_commit($this->conn_id);
 	}
 
 	// --------------------------------------------------------------------
@@ -385,20 +383,14 @@ class CI_DB_oci8_driver extends CI_DB {
 	 */
 	public function trans_rollback()
 	{
-		if ( ! $this->trans_enabled)
-		{
-			return TRUE;
-		}
-
 		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ($this->_trans_depth > 0)
+		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
 		{
 			return TRUE;
 		}
 
-		$ret = oci_rollback($this->conn_id);
-		$this->_commit = OCI_COMMIT_ON_SUCCESS;
-		return $ret;
+		$this->commit_mode = OCI_COMMIT_ON_SUCCESS;
+		return oci_rollback($this->conn_id);
 	}
 
 	// --------------------------------------------------------------------
@@ -469,7 +461,7 @@ class CI_DB_oci8_driver extends CI_DB {
 	 * the specified database
 	 *
 	 * @param	string
-	 * @return	string
+	 * @return	int
 	 */
 	public function count_all($table = '')
 	{
@@ -501,11 +493,11 @@ class CI_DB_oci8_driver extends CI_DB {
 	 */
 	protected function _list_tables($prefix_limit = FALSE)
 	{
-		$sql = "SELECT TABLE_NAME FROM ALL_TABLES";
+		$sql = 'SELECT TABLE_NAME FROM ALL_TABLES';
 
-		if ($prefix_limit !== FALSE AND $this->dbprefix != '')
+		if ($prefix_limit !== FALSE && $this->dbprefix != '')
 		{
-			$sql .= " WHERE TABLE_NAME LIKE '".$this->escape_like_str($this->dbprefix)."%' ".sprintf($this->_like_escape_str, $this->_like_escape_chr);
+			return $sql." WHERE TABLE_NAME LIKE '".$this->escape_like_str($this->dbprefix)."%' ".sprintf($this->_like_escape_str, $this->_like_escape_chr);
 		}
 
 		return $sql;
@@ -523,7 +515,7 @@ class CI_DB_oci8_driver extends CI_DB {
 	 */
 	protected function _list_columns($table = '')
 	{
-		return "SELECT COLUMN_NAME FROM all_tab_columns WHERE table_name = '$table'";
+		return 'SELECT COLUMN_NAME FROM all_tab_columns WHERE table_name = \''.$table.'\'';
 	}
 
 	// --------------------------------------------------------------------
@@ -538,7 +530,7 @@ class CI_DB_oci8_driver extends CI_DB {
 	 */
 	protected function _field_data($table)
 	{
-		return "SELECT * FROM ".$table." where rownum = 1";
+		return 'SELECT * FROM '.$table.' WHERE rownum = 1';
 	}
 
 	// --------------------------------------------------------------------
@@ -593,24 +585,20 @@ class CI_DB_oci8_driver extends CI_DB {
 		{
 			if (strpos($item, '.'.$id) !== FALSE)
 			{
-				$str = $this->_escape_char. str_replace('.', $this->_escape_char.'.', $item);
+				$item = str_replace('.', $this->_escape_char.'.', $item);
 
 				// remove duplicates if the user already included the escape
-				return preg_replace('/['.$this->_escape_char.']+/', $this->_escape_char, $str);
+				return preg_replace('/['.$this->_escape_char.']+/', $this->_escape_char, $this->_escape_char.$item);
 			}
 		}
 
 		if (strpos($item, '.') !== FALSE)
 		{
-			$str = $this->_escape_char.str_replace('.', $this->_escape_char.'.'.$this->_escape_char, $item).$this->_escape_char;
-		}
-		else
-		{
-			$str = $this->_escape_char.$item.$this->_escape_char;
+			$item = str_replace('.', $this->_escape_char.'.'.$this->_escape_char, $item);
 		}
 
 		// remove duplicates if the user already included the escape
-		return preg_replace('/['.$this->_escape_char.']+/', $this->_escape_char, $str);
+		return preg_replace('/['.$this->_escape_char.']+/', $this->_escape_char, $this->_escape_char.$item.$this->_escape_char);
 	}
 
 	// --------------------------------------------------------------------
@@ -626,12 +614,7 @@ class CI_DB_oci8_driver extends CI_DB {
 	 */
 	protected function _from_tables($tables)
 	{
-		if ( ! is_array($tables))
-		{
-			$tables = array($tables);
-		}
-
-		return implode(', ', $tables);
+		return is_array($tables) ? implode(', ', $tables) : $tables;
 	}
 
 	// --------------------------------------------------------------------
@@ -648,7 +631,7 @@ class CI_DB_oci8_driver extends CI_DB {
 	 */
 	protected function _insert($table, $keys, $values)
 	{
-		return "INSERT INTO ".$table." (".implode(', ', $keys).") VALUES (".implode(', ', $values).")";
+		return 'INSERT INTO '.$table.' ('.implode(', ', $keys).') VALUES ('.implode(', ', $values).')';
 	}
 
 	// --------------------------------------------------------------------
@@ -670,12 +653,10 @@ class CI_DB_oci8_driver extends CI_DB {
 
 		for ($i = 0, $c = count($values); $i < $c; $i++)
 		{
-			$sql .= '	INTO ' . $table . ' (' . $keys . ') VALUES ' . $values[$i] . "\n";
+			$sql .= '	INTO '.$table.' ('.$keys.') VALUES '.$values[$i].'\n';
 		}
 
-		$sql .= 'SELECT * FROM dual';
-
-		return $sql;
+		return $sql.'SELECT * FROM dual';
 	}
 
 	// --------------------------------------------------------------------
@@ -696,20 +677,13 @@ class CI_DB_oci8_driver extends CI_DB {
 	{
 		foreach ($values as $key => $val)
 		{
-			$valstr[] = $key." = ".$val;
+			$valstr[] = $key.' = '.$val;
 		}
 
-		$limit = ( ! $limit) ? '' : ' LIMIT '.$limit;
-
-		$orderby = (count($orderby) >= 1)?' ORDER BY '.implode(", ", $orderby):'';
-
-		$sql = "UPDATE ".$table." SET ".implode(', ', $valstr);
-
-		$sql .= ($where != '' AND count($where) >=1) ? " WHERE ".implode(" ", $where) : '';
-
-		$sql .= $orderby.$limit;
-
-		return $sql;
+		return 'UPDATE '.$table.' SET '.implode(', ', $valstr)
+			.(($where != '' && count($where) > 0) ? ' WHERE '.implode(' ', $where) : '')
+			.(count($orderby) > 0 ? ' ORDER BY '.implode(', ', $orderby) : '')
+			.( ! $limit ? '' : ' LIMIT '.$limit);
 	}
 
 	// --------------------------------------------------------------------
@@ -726,7 +700,7 @@ class CI_DB_oci8_driver extends CI_DB {
 	 */
 	protected function _truncate($table)
 	{
-		return "TRUNCATE TABLE ".$table;
+		return 'TRUNCATE TABLE '.$table;
 	}
 
 	// --------------------------------------------------------------------
@@ -744,22 +718,18 @@ class CI_DB_oci8_driver extends CI_DB {
 	protected function _delete($table, $where = array(), $like = array(), $limit = FALSE)
 	{
 		$conditions = '';
-
 		if (count($where) > 0 OR count($like) > 0)
 		{
-			$conditions = "\nWHERE ";
-			$conditions .= implode("\n", $this->ar_where);
+			$conditions = "\nWHERE ".implode("\n", $this->ar_where);
 
 			if (count($where) > 0 && count($like) > 0)
 			{
-				$conditions .= " AND ";
+				$conditions .= ' AND ';
 			}
 			$conditions .= implode("\n", $like);
 		}
 
-		$limit = ( ! $limit) ? '' : ' LIMIT '.$limit;
-
-		return "DELETE FROM ".$table.$conditions.$limit;
+		return 'DELETE FROM '.$table.$conditions.( ! $limit ? '' : ' LIMIT '.$limit);
 	}
 
 	// --------------------------------------------------------------------
@@ -776,18 +746,9 @@ class CI_DB_oci8_driver extends CI_DB {
 	 */
 	protected function _limit($sql, $limit, $offset)
 	{
-		$limit = $offset + $limit;
-		$newsql = "SELECT * FROM (select inner_query.*, rownum rnum FROM ($sql) inner_query WHERE rownum < $limit)";
-
-		if ($offset != 0)
-		{
-			$newsql .= " WHERE rnum >= $offset";
-		}
-
-		// remember that we used limits
 		$this->limit_used = TRUE;
-
-		return $newsql;
+		return 'SELECT * FROM (SELECT inner_query.*, rownum rnum FROM ('.$sql.') inner_query WHERE rownum < '.($offset + $limit).')'
+			.($offset != 0 ? ' WHERE rnum >= '.$offset : '');
 	}
 
 	// --------------------------------------------------------------------
diff --git a/system/database/drivers/oci8/oci8_forge.php b/system/database/drivers/oci8/oci8_forge.php
index 8285a29d2..4b2eccae5 100644
--- a/system/database/drivers/oci8/oci8_forge.php
+++ b/system/database/drivers/oci8/oci8_forge.php
@@ -42,6 +42,7 @@ class CI_DB_oci8_forge extends CI_DB_forge {
 	 */
 	public function _create_database($name)
 	{
+		// Not supported - schemas in Oracle are actual usernames
 		return FALSE;
 	}
 
@@ -55,6 +56,7 @@ class CI_DB_oci8_forge extends CI_DB_forge {
 	 */
 	public function _drop_database($name)
 	{
+		// Not supported - schemas in Oracle are actual usernames
 		return FALSE;
 	}
 
@@ -68,7 +70,7 @@ class CI_DB_oci8_forge extends CI_DB_forge {
 	 * @param	mixed	primary key(s)
 	 * @param	mixed	key(s)
 	 * @param	bool	should 'IF NOT EXISTS' be added to the SQL
-	 * @return	bool
+	 * @return	string
 	 */
 	public function _create_table($table, $fields, $primary_keys, $keys, $if_not_exists)
 	{
@@ -128,7 +130,7 @@ class CI_DB_oci8_forge extends CI_DB_forge {
 					$key = array($this->db->protect_identifiers($key));
 				}
 
-				$sql .= ",\n\tUNIQUE COLUMNS (".implode(', ', $key).")";
+				$sql .= ",\n\tUNIQUE COLUMNS (".implode(', ', $key).')';
 			}
 		}
 
@@ -140,11 +142,11 @@ class CI_DB_oci8_forge extends CI_DB_forge {
 	/**
 	 * Drop Table
 	 *
-	 * @return	bool
+	 * @return	string
 	 */
 	public function _drop_table($table)
 	{
-		return FALSE;
+		return 'DROP TABLE '.$this->db->protect_identifiers($table);
 	}
 
 	// --------------------------------------------------------------------
@@ -169,33 +171,15 @@ class CI_DB_oci8_forge extends CI_DB_forge {
 		$sql = 'ALTER TABLE '.$this->db->protect_identifiers($table).' '.$alter_type.' '.$this->db->protect_identifiers($column_name);
 
 		// DROP has everything it needs now.
-		if ($alter_type == 'DROP')
+		if ($alter_type === 'DROP')
 		{
 			return $sql;
 		}
 
-		$sql .= " $column_definition";
-
-		if ($default_value != '')
-		{
-			$sql .= " DEFAULT \"$default_value\"";
-		}
-
-		if ($null === NULL)
-		{
-			$sql .= ' NULL';
-		}
-		else
-		{
-			$sql .= ' NOT NULL';
-		}
-
-		if ($after_field != '')
-		{
-			return $sql.' AFTER '.$this->db->protect_identifiers($after_field);
-		}
-
-		return $sql;
+		return $sql.' '.$column_definition
+			.($default_value != '' ? ' DEFAULT "'.$default_value.'"' : '')
+			.($null === NULL ? ' NULL' : ' NOT NULL')
+			.($after_field != '' ? ' AFTER '.$this->db->protect_identifiers($after_field) : '');
 
 	}
 
diff --git a/system/database/drivers/oci8/oci8_result.php b/system/database/drivers/oci8/oci8_result.php
index c3f775730..aad24cfd9 100644
--- a/system/database/drivers/oci8/oci8_result.php
+++ b/system/database/drivers/oci8/oci8_result.php
@@ -39,6 +39,12 @@ class CI_DB_oci8_result extends CI_DB_result {
 	public $stmt_id;
 	public $curs_id;
 	public $limit_used;
+	public $commit_mode;
+
+	/* Overwriting the parent here, so we have a way to know if it's
+	 * already called or not:
+	 */
+	public $num_rows;
 
 	public function __construct(&$driver_object)
 	{
@@ -46,28 +52,32 @@ class CI_DB_oci8_result extends CI_DB_result {
 		$this->stmt_id = $driver_object->stmt_id;
 		$this->curs_id = $driver_object->curs_id;
 		$this->limit_used = $driver_object->limit_used;
+		$this->commit_mode =& $driver_object->commit_mode;
 		$driver_object->stmt_id = FALSE;
 	}
 
 	/**
 	 * Number of rows in the result set.
 	 *
-	 * Oracle doesn't have a graceful way to retun the number of rows
+	 * Oracle doesn't have a graceful way to return the number of rows
 	 * so we have to use what amounts to a hack.
 	 *
 	 * @return	int
 	 */
 	public function num_rows()
 	{
-		if ($this->num_rows === 0 && count($this->result_array()) > 0)
+		if ( ! is_int($this->num_rows))
 		{
-			$this->num_rows = count($this->result_array());
-			@oci_execute($this->stmt_id, OCI_DEFAULT);
-
-			if ($this->curs_id)
+			if (count($this->result_array) > 0)
+			{
+				return $this->num_rows = count($this->result_array);
+			}
+			elseif (count($this->result_object) > 0)
 			{
-				@oci_execute($this->curs_id, OCI_DEFAULT);
+				return $this->num_rows = count($this->result_object);
 			}
+
+			return $this->num_rows = count($this->result_array());
 		}
 
 		return $this->num_rows;
@@ -85,12 +95,7 @@ class CI_DB_oci8_result extends CI_DB_result {
 		$count = @oci_num_fields($this->stmt_id);
 
 		// if we used a limit we subtract it
-		if ($this->limit_used)
-		{
-			$count = $count - 1;
-		}
-
-		return $count;
+		return ($this->limit_used) ? $count - 1 : $count;
 	}
 
 	// --------------------------------------------------------------------
@@ -126,10 +131,10 @@ class CI_DB_oci8_result extends CI_DB_result {
 		$retval = array();
 		for ($c = 1, $fieldCount = $this->num_fields(); $c <= $fieldCount; $c++)
 		{
-			$F			= new stdClass();
-			$F->name		= oci_field_name($this->stmt_id, $c);
-			$F->type		= oci_field_type($this->stmt_id, $c);
-			$F->max_length		= oci_field_size($this->stmt_id, $c);
+			$F		= new stdClass();
+			$F->name	= oci_field_name($this->stmt_id, $c);
+			$F->type	= oci_field_type($this->stmt_id, $c);
+			$F->max_length	= oci_field_size($this->stmt_id, $c);
 
 			$retval[] = $F;
 		}
@@ -151,6 +156,17 @@ class CI_DB_oci8_result extends CI_DB_result {
 			oci_free_statement($this->result_id);
 			$this->result_id = FALSE;
 		}
+
+		if (is_resource($this->stmt_id))
+		{
+			oci_free_statement($this->stmt_id);
+		}
+
+		if (is_resource($this->curs_id))
+		{
+			oci_cancel($this->curs_id);
+			$this->curs_id = NULL;
+		}
 	}
 
 	// --------------------------------------------------------------------
@@ -180,13 +196,13 @@ class CI_DB_oci8_result extends CI_DB_result {
 	protected function _fetch_object()
 	{
 		$id = ($this->curs_id) ? $this->curs_id : $this->stmt_id;
-		return @oci_fetch_object($id);
+		return oci_fetch_object($id);
 	}
 
 	// --------------------------------------------------------------------
 
 	/**
-	 * Query result.  "array" version.
+	 * Query result. Array version.
 	 *
 	 * @return	array
 	 */
@@ -196,14 +212,433 @@ class CI_DB_oci8_result extends CI_DB_result {
 		{
 			return $this->result_array;
 		}
+		elseif (count($this->result_object) > 0)
+		{
+			for ($i = 0, $c = count($this->result_object); $i < $c; $i++)
+			{
+				$this->result_array[$i] = (array) $this->result_object[$i];
+			}
+
+			return $this->result_array;
+		}
+		elseif (is_array($this->row_data))
+		{
+			if (count($this->row_data) === 0)
+			{
+				return $this->result_array;
+			}
+			else
+			{
+				$row_index = count($this->row_data);
+			}
+		}
+		else
+		{
+			$row_index = 0;
+			$this->row_data = array();
+		}
 
 		$row = NULL;
 		while ($row = $this->_fetch_assoc())
 		{
-			$this->result_array[] = $row;
+			$this->row_data[$row_index++] = $row;
+		}
+
+		// Un-comment the following line, in case it becomes needed
+		// $this->_data_seek();
+		return $this->result_array = $this->row_data;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Query result. "object" version.
+	 *
+	 * @return	array
+	 */
+	public function result_object()
+	{
+		if (count($this->result_object) > 0)
+		{
+			return $this->result_object;
+		}
+		elseif (count($this->result_array) > 0)
+		{
+			for ($i = 0, $c = count($this->result_array); $i < $c; $i++)
+			{
+				$this->result_object[] = (object) $this->result_array[$i];
+			}
+
+			return $this->result_object;
+		}
+		elseif (is_array($this->row_data))
+		{
+			if (count($this->row_data) === 0)
+			{
+				return $this->result_object;
+			}
+			else
+			{
+				$row_index = count($this->row_data);
+				for ($i = 0; $i < $row_index; $i++)
+				{
+					$this->result_object[$i] = (object) $this->row_data[$i];
+				}
+			}
+		}
+		else
+		{
+			$row_index = 0;
+			$this->row_data = array();
+		}
+
+		$row = NULL;
+		while ($row = $this->_fetch_object())
+		{
+			$this->row_data[$row_index] = (array) $row;
+			$this->result_object[$row_index++] = $row;
+		}
+
+		// Un-comment the following line, in case it becomes needed
+		// $this->_data_seek();
+		return $this->result_object;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Query result. Custom object version.
+	 *
+	 * @param	string	class name used to instantiate rows to
+	 * @return	array
+	 */
+	public function custom_result_object($class_name)
+	{
+		if (isset($this->custom_result_object[$class_name]))
+		{
+			return $this->custom_result_object[$class_name];
+		}
+
+		if ( ! class_exists($class_name) OR $this->result_id === FALSE OR $this->num_rows() === 0)
+		{
+			return array();
+		}
+
+		/* Even if we didn't have result_array or result_object
+		 * set prior to custom_result_object() being called,
+		 * num_rows() has already done so.
+		 * Pass by reference, as we don't know how
+		 * large it might be and we don't want 1000 row
+		 * sets being copied.
+		 */
+		if (count($this->result_array) > 0)
+		{
+			$data = &$this->result_array;
+		}
+		elseif (count($this->result_object) > 0)
+		{
+			$data = &$this->result_object;
+		}
+
+		$this->custom_result_object[$class_name] = array();
+		for ($i = 0, $c = count($data); $i < $c; $i++)
+		{
+			$this->custom_result_object[$class_name][$i] = new $class_name();
+			foreach ($data[$i] as $key => $value)
+			{
+				$this->custom_result_object[$class_name][$i]->$key = $value;
+			}
+		}
+
+		return $this->custom_result_object[$class_name];
+	}
+
+	// --------------------------------------------------------------------
+
+	/* Single row result.
+	 *
+	 * Acts as a wrapper for row_object(), row_array()
+	 * and custom_row_object(). Also used by first_row(), next_row()
+	 * and previous_row().
+	 *
+	 * @param	int	row index
+	 * @param	string	('object', 'array' or a custom class name)
+	 * @return	mixed	whatever was passed to the second parameter
+	 */
+	public function row($n = 0, $type = 'object')
+	{
+		if ($type === 'object')
+		{
+			return $this->row_object($n);
+		}
+		elseif ($type === 'array')
+		{
+			return $this->row_array($n);
+		}
+
+		return $this->custom_row_object($n, $type);
+	}
+
+	// --------------------------------------------------------------------
+
+	/* Single row result. Array version.
+	 *
+	 * @param	int	row index
+	 * @return	array
+	 */
+	public function row_array($n = 0)
+	{
+		// Make sure $n is not a string
+		if ( ! is_int($n))
+		{
+			$n = (int) $n;
+		}
+
+		/* If row_data is initialized, it means that we've already tried
+		 * (at least) to fetch some data, so ... check if we already have
+		 * this row.
+		*/
+		if (is_array($this->row_data))
+		{
+			/* If we already have row_data[$n] - return it.
+			 *
+			 * If we enter the elseif, there's a number of reasons to
+			 * return an empty array:
+			 *
+			 *	- count($this->row_data) === 0 means there are no results
+			 *	- num_rows being set, result_array and/or result_object
+			 *	  having count() > 0 means that we've already fetched all
+			 *	  data and $n is greater than our highest row index available
+			 *	- $n < $this->current_row means that if such row existed,
+			 *	  we would've already returned it, therefore $n is an
+			 *	  invalid index
+			 */
+			if (isset($this->row_data[$n])) // We already have this row
+			{
+				$this->current_row = $n;
+				return $this->row_data[$n];
+			}
+			elseif (count($this->row_data) === 0 OR is_int($this->num_rows)
+				OR count($this->result_array) > 0 OR count($this->result_object) > 0
+				OR $n < $this->current_row)
+			{
+				// No such row exists
+				return array();
+			}
+
+			// Get the next row index that would actually need to be fetched
+			$current_row = ($this->current_row < count($this->row_data)) ? count($this->row_data) : $this->current_row + 1;
+		}
+		else
+		{
+			$current_row = $this->current_row = 0;
+			$this->row_data = array();
+		}
+
+		/* Fetch more data, if available
+		 *
+		 * NOTE: Operator precedence is important here, if you change
+		 *	 'AND' with '&&' - it WILL BREAK the results, as
+		 *	 $row will be assigned the scalar value of both
+		 *	 expressions!
+		 */
+		while ($row = $this->_fetch_assoc() AND $current_row <= $n)
+		{
+			$this->row_data[$current_row++] = $row;
 		}
 
-		return $this->result_array;
+		// This would mean that there's no (more) data to fetch
+		if ( ! is_array($this->row_data) OR ! isset($this->row_data[$n]))
+		{
+			// Cache what we already have
+			if (is_array($this->row_data))
+			{
+				$this->num_rows = count($this->row_data);
+				/* Usually, row_data could have less elements than result_array,
+				 * but at this point - they should be exactly the same.
+				 */
+				$this->result_array = $this->row_data;
+			}
+			else
+			{
+				$this->num_rows = 0;
+			}
+
+			return array();
+		}
+
+		$this->current_row = $n;
+		return $this->row_data[$n];
+	}
+
+	// --------------------------------------------------------------------
+
+	/* Single row result. Object version.
+	 *
+	 * @param	int	row index
+	 * @return	mixed	object if row found; empty array if not
+	 */
+	public function row_object($n = 0)
+	{
+		// Make sure $n is not a string
+		if ( ! is_int($n))
+		{
+			$n = (int) $n;
+		}
+		/* Logic here is exactly the same as in row_array,
+		 * except we have to cast row_data[$n] to an object.
+		 *
+		 * If we already have result_object though - we can
+		 * directly return from it.
+		 */
+		if (isset($this->result_object[$n]))
+		{
+			$this->current_row = $n;
+			// Set this, if not already done.
+			if ( ! is_int($this->num_rows))
+			{
+				$this->num_rows = count($this->result_object);
+			}
+
+			return $this->result_object[$n];
+		}
+
+		$row = $this->row_array($n);
+		// Cast only if the row exists
+		if (count($row) > 0)
+		{
+			$this->current_row = $n;
+			return (object) $row;
+		}
+
+		return array();
+	}
+
+	// --------------------------------------------------------------------
+
+	/* Single row result. Custom object version.
+	 *
+	 * @param	int	row index
+	 * @param	string	custom class name
+	 * @return	mixed	custom object if row found; empty array otherwise
+	 */
+	public function custom_row_object($n = 0, $class_name)
+	{
+		// Make sure $n is not a string
+		if ( ! is_int($n))
+		{
+			$n = (int) $n;
+		}
+
+		if (array_key_exists($class_name, $this->custom_result_object))
+		{
+			/* We already have a the whole result set with this class_name,
+			 * return the specified row if it exists, and an empty array if
+			 * it doesn't.
+			 */
+			if (isset($this->custom_result_object[$class_name][$n]))
+			{
+				$this->current_row = $n;
+				return $this->custom_result_object[$class_name][$n];
+			}
+			else
+			{
+				return array();
+			}
+		}
+		elseif ( ! class_exists($class_name)) // No such class exists
+		{
+			return array();
+		}
+
+		$row = $this->row_array($n);
+		// An array would mean that the row doesn't exist
+		if (is_array($row))
+		{
+			return $row;
+		}
+
+		// Convert to the desired class and return
+		$row_object = new $class_name();
+		foreach ($row as $key => $value)
+		{
+			$row_object->$key = $value;
+		}
+
+		$this->current_row = $n;
+		return $row_object;
+	}
+
+	// --------------------------------------------------------------------
+
+	/* First row result.
+	 *
+	 * @param	string	('object', 'array' or a custom class name)
+	 * @return	mixed	whatever was passed to the second parameter
+	 */
+	public function first_row($type = 'object')
+	{
+		return $this->row(0, $type);
+	}
+
+	// --------------------------------------------------------------------
+
+	/* Last row result.
+	 *
+	 * @param	string	('object', 'array' or a custom class name)
+	 * @return	mixed	whatever was passed to the second parameter
+	 */
+	public function last_row($type = 'object')
+	{
+		$result = &$this->result($type);
+		if ( ! isset($this->num_rows))
+		{
+			$this->num_rows = count($result);
+		}
+		$this->current_row = $this->num_rows - 1;
+		return $result[$this->current_row];
+	}
+
+	// --------------------------------------------------------------------
+
+	/* Next row result.
+	 *
+	 * @param	string	('object', 'array' or a custom class name)
+	 * @return	mixed	whatever was passed to the second parameter
+	 */
+	public function next_row($type = 'object')
+	{
+		if (is_array($this->row_data))
+		{
+			$count = count($this->row_data);
+			if ($this->current_row > $count OR ($this->current_row === 0 && $count === 0))
+			{
+				$n = $count;
+			}
+			else
+			{
+				$n = $this->current_row + 1;
+			}
+		}
+		else
+		{
+			$n = 0;
+		}
+
+		return $this->row($n, $type);
+	}
+
+	// --------------------------------------------------------------------
+
+	/* Previous row result.
+	 *
+	 * @param	string	('object', 'array' or a custom class name)
+	 * @return	mixed	whatever was passed to the second parameter
+	 */
+	public function previous_row($type = 'object')
+	{
+		$n = ($this->current_row !== 0) ? $this->current_row - 1 : 0;
+		return $this->row($n, $type);
 	}
 
 	// --------------------------------------------------------------------
@@ -213,13 +648,54 @@ class CI_DB_oci8_result extends CI_DB_result {
 	 *
 	 * Moves the internal pointer to the desired offset. We call
 	 * this internally before fetching results to make sure the
-	 * result set starts at zero
+	 * result set starts at zero.
 	 *
-	 * @return	array
+	 * Oracle's PHP extension doesn't have an easy way of doing this
+	 * and the only workaround is to (re)execute the statement or cursor
+	 * in order to go to the first (zero) index of the result set.
+	 * Then, we would need to "dummy" fetch ($n - 1) rows to get to the
+	 * right one.
+	 *
+	 * This is as ridiculous as it sounds and it's the reason why every
+	 * other method that is fetching data tries to use an already "cached"
+	 * result set. Keeping this just in case it becomes needed at
+	 * some point in the future, but it will only work for resetting the
+	 * pointer to zero.
+	 *
+	 * @return	bool
 	 */
-	protected function _data_seek($n = 0)
+	protected function _data_seek()
 	{
-		return FALSE; // Not needed
+		/* The PHP manual says that if OCI_NO_AUTO_COMMIT mode
+		 * is used, and oci_rollback() and/or oci_commit() are
+		 * not subsequently called - this will cause an unnecessary
+		 * rollback to be triggered at the end of the script execution.
+		 *
+		 * Therefore we'll try to avoid using that mode flag
+		 * if we're not currently in the middle of a transaction.
+		 */
+		if ($this->commit_mode !== OCI_COMMIT_ON_SUCCESS)
+		{
+			$result = @oci_execute($this->stmt_id, $this->commit_mode);
+		}
+		else
+		{
+			$result = @oci_execute($this->stmt_id);
+		}
+
+		if ($result && $this->curs_id)
+		{
+			if ($this->commit_mode !== OCI_COMMIT_ON_SUCCESS)
+			{
+				return @oci_execute($this->curs_id, $this->commit_mode);
+			}
+			else
+			{
+				return @oci_execute($this->curs_id);
+			}
+		}
+
+		return $result;
 	}
 
 }
diff --git a/system/database/drivers/oci8/oci8_utility.php b/system/database/drivers/oci8/oci8_utility.php
index e303fb6cb..efb4bca02 100644
--- a/system/database/drivers/oci8/oci8_utility.php
+++ b/system/database/drivers/oci8/oci8_utility.php
@@ -37,11 +37,14 @@ class CI_DB_oci8_utility extends CI_DB_utility {
 	/**
 	 * List databases
 	 *
-	 * @return	bool
+	 * Generates a platform-specific query so that we get a list of schemas
+	 * Those are actually usernames in Oracle.
+	 *
+	 * @return	string
 	 */
 	public function _list_databases()
 	{
-		return FALSE;
+		return 'SELECT username FROM dba_users';
 	}
 
 	// --------------------------------------------------------------------
@@ -56,7 +59,7 @@ class CI_DB_oci8_utility extends CI_DB_utility {
 	 */
 	public function _optimize_table($table)
 	{
-		return FALSE; // Is this supported in Oracle?
+		return FALSE; // Not supported in Oracle
 	}
 
 	// --------------------------------------------------------------------
@@ -71,7 +74,7 @@ class CI_DB_oci8_utility extends CI_DB_utility {
 	 */
 	public function _repair_table($table)
 	{
-		return FALSE; // Is this supported in Oracle?
+		return FALSE; // Not supported in Oracle
 	}
 
 	// --------------------------------------------------------------------